Bipedal robot

ABSTRACT

A bipedal robot has an upper body  1  which comprises a higher upper body  5  and a lower upper body  6.  The higher upper body  5  and the lower upper body  6  are coupled to each other by a rotating mechanism  13  so as to be rotatable with respect to each other about a vertical axis C of rotation. Two legs  2  extend from the lower upper body  6,  and two arms  3  extend from respective shoulders  14  on opposite sides of the higher upper body  5.  The higher upper body  5  of the robot has a thickness D in a forward/rearward direction and the lower upper body  6  has a width Wd in a lateral direction, the thickness D and the width Wd being smaller than the width Wu in a lateral direction of the robot at shoulders  14  (shoulder width Wu). An electric energy storage device  8  as a power supply for operating the robot is mounted in the higher upper body  5,  and an electronic circuit unit  11  for controlling operation of the robot is mounted in the lower upper body  6.  With this robot arrangement, the robot is capable of increasing its working capability without impairing the stability of the attitude when the robot works.

TECHNICAL FIELD

[0001] The present invention relates to a bipedal robot.

BACKGROUND ART

[0002] Bipedal robots which have in recent years been proposed forpractical use by the present applicant and others and which have beenknown in general are basically human-shaped robots. Like human beings,they have two legs extending from a hip at the lower end of an upperbody (torso), and two arms extending from shoulders on the left andright opposite sides of the upper body.

[0003] Robots which carry an electric energy storage device as a powersupply for operating the robots also have an electronic circuit unit(controller) that is usually mounted on an upper body of the robot forcontrolling operation of the electric energy storage device and therobot.

[0004] For a bipedal robot to be able to carry out various works in avariety of environments, it is desirable that the tip ends of the armsof the robot reach as far a position as possible.

[0005] If arms are elongated, then the tip ends of the arms can reach afar position. However, if arms are too elongated, then the robot tendsto lose the stability of its attitude when the arms are extended andperform some work, and finds it difficult to work with the arms at alocation close to the robot.

[0006] When a conventional bipedal robot is to grip, with its arms, anobject that is present laterally of the robot, the robot basically movesthe legs to direct the robot in its entirety to face the object. Inenvironments where the footing is unstable or limited to a small area,however, it may be difficult to move the legs to change the direction ofthe robot in its entirety. In those environments, the robot practicallyfails to grip the object.

[0007] The present invention has been made in view of the abovebackground. It is an object of the present invention to provide abipedal robot which is capable of increasing its working capabilitywithout impairing the stability of the attitude when the robot works.

[0008] Another object of the present invention is to provide a bipedalrobot whose maintenance can easily be carried out.

DISCLOSURE OF THE INVENTION

[0009] In order to achieve the above objects, a bipedal robot accordingto the present invention which has two legs extending from a lower endof an upper body and two arms extending from shoulders on opposite sidesof the upper body is characterized in that said upper body comprises ahigher upper body and a lower upper body, said higher upper body andsaid lower upper body being coupled to each other by a rotatingmechanism having a vertical axis of rotation, and being rotatable withrespect to each other about said axis of rotation, and said two armsextend from said higher upper body and said two legs extend from saidlower upper body.

[0010] Prior to describing the present invention in greater detail, asupplementary description of some terms used in the presentspecification is given below. In the present specification, thedirection of a line interconnection two shoulders on opposite sides of ahigher upper body of a robot (the direction in which the shoulders areparallel to each other) is referred to as a lateral direction of thehigher upper body, and the direction perpendicular to the lateraldirection and the vertical direction is referred to as aforward/rearward direction of the higher upper body. The direction inwhich two legs of the robot are parallel to each other at the time therobot is in an upstanding state is referred to as a lateral direction ofthe lower upper body, and the direction perpendicular to the lateraldirection and the vertical direction is referred to as aforward/rearward direction of the lower upper body or a forward/rearwarddirection of the robot.

[0011] With the invention as described above, when the higher upper bodyis rotated clockwise or counterclockwise with respect to the lower upperbody about the axis of rotation of the rotating mechanism, from a statein which a forward/rearward direction of the higher upper body and aforward/rearward direction of the lower upper body are aligned with eachother (the state will hereinafter referred to as a basic attitude stateof the upper body), for example, one of shoulders on left and rightopposite sides of the higher upper body is moved forwardly in theforward/rearward direction of the lower upper body. Therefore, when thearm extending from the forwardly moved shoulder is extended forwardly ofthe lower upper body, a distal end of the arm can reach a fartherposition than when the upper body is in the basic attitude state. Thus,the arms can be relatively short, but can grip a relatively far object.At this time, since the other shoulder and the arm extending therefromare moved rearwardly of the lower upper body, when the arm extendingfrom the forwardly moved shoulder is extended forwardly, the armextending from the rearwardly moved shoulder can easily keep the robotbalanced in weight in the forward/rearward direction (theforward/rearward direction of the lower upper body), thus easilyachieving the stability of the attitude of the robot.

[0012] By thus rotating the higher upper body with respect to the lowerupper body, the higher upper body from which the two arms extend can beoriented in various directions without the need for moving the two legsextending from the lower upper body. Therefore, even in an environmentwhere the footing is unstable, the two legs extending from the lowerupper body can remain on an area where the robot can stand stably, andan object present laterally of the lower upper body with respect to theforward/rearward direction can easily be gripped by the arms.

[0013] The bipedal robot according to the present invention is thuscapable of increasing its working capability without impairing thestability of the attitude when the robot works.

[0014] According to the present invention, furthermore, said higherupper body preferably has a thickness in the forward/rearward directionwhich is smaller than the width in the lateral direction of the robot atsaid shoulders, and said lower upper body preferably has a width in thelateral direction which is smaller than the width in the lateraldirection of the robot at said shoulders.

[0015] With this arrangement, when the higher upper body is rotatedabout 90°, for example, with respect to the lower upper body about theaxis of rotation of the rotating mechanism from the basic attitude stateof said upper body, the maximum width in the lateral direction of therobot can be smaller than the maximum width in the basic attitude stateof the upper body (which is the same as the width in the lateraldirection of the robot at the shoulders). Therefore, by rotating thehigher upper body with respect to the lower upper body, the robot canmove (walk) in a narrow passage through which the robot cannot pass ifin the basic attitude state.

[0016] If the bipedal robot has an electric energy storage device as apower supply for operating the robot and an electronic circuit unit forcontrolling operation of the robot, then a problem would arise as towhich of the higher upper body and the lower upper body the electricenergy storage device and the electronic circuit unit have to be mountedin. Mounting both the electric energy storage device and the electroniccircuit unit in either one of the higher upper body and the lower upperbody would not be preferable as that one of the higher upper body andthe lower upper body would become excessively large. The electric energystorage device mounted on the robot as a power supply for operating therobot needs to be of a relatively large capacity, and hence isrelatively large in size and weight. Therefore, the location where theelectric energy storage device is mounted tends to affect the stabilityof the robot attitude when the robot walks and works.

[0017] It is customary to control the attitude stabilization of abipedal robot based on an inverted pendulum-type dynamic model asdisclosed in Japanese laid-open patent publication No. 5-337849 or U.S.Pat. No. 5,459,659 by the present applicant. The attitude stabilizationis controlled by controlling a torque around ankles of the robot withthe behavioral characteristics of perturbation of the position of theupper body of the robot being simulated by the behavioralcharacteristics of an inverted pendulum. A robot under such attitudestabilization control can achieve better robot attitude stability if thecenter of gravity of the overall robot is in a higher position than itis in a lower position (a vertical position closer to the floor that iscontacted by the feet of the robot).

[0018] According to the present invention, if the bipedal robot has anelectric energy storage device as a power supply for operating the robotand an electronic circuit unit for controlling operation of the robot,then the electric energy storage device is mounted in the higher upperbody and the electronic circuit unit is mounted in the lower upper body.

[0019] With the above arrangement, since the electric energy storagedevice which is a heavy object is mounted in the higher upper body, thecenter of gravity of the overall robot including the electric energystorage device and the electronic circuit unit is in a higher positionon the robot, thus increasing the stability of the robot attitude whenthe robot walks and works. Because the electronic circuit unit ispresent below the electric energy storage device, heat generated by theelectric energy storage device during operation of the robot (while therobot is walking or working) is hardly transmitted to the electroniccircuit unit. As a consequence, only the heat generated by theelectronic circuit unit is applied to the electronic circuit unit, andthe electronic circuit unit is prevented from reaching excessively hightemperatures.

[0020] The present invention is optimum for a bipedal robot whoseattitude stabilization is controlled based on an inverted pendulum-typedynamic model, as described above.

[0021] With the bipedal robot according to the present in which theelectric energy storage device and the electronic circuit unit aremounted, a holder is preferably fixed to said higher upper body forsuspending and holding said robot.

[0022] While the robot is being inactivated (its power supply is turnedoff and the robot cannot stand on its own), the holder can be held tosuspend the robot. Since the holder is fixed to the higher upper body inwhich the heavy electric energy storage device is mounted, the robot canbe suspended and held while being kept in an appropriate attitude inwhich it is unlikely for various parts of the robot to be subjected toburdens (excessive loads or the like) when the robot is suspended.Inasmuch as the heavy electric energy storage device is mounted in thehigher upper body to which the holder is fixed, while the robot is beingsuspended, the weight of the portion of the robot below the rotatingmechanism is relatively small, and an excessive load (a tensile load) isprevented from acting on the rotating mechanism. Though it is difficultfor the rotating mechanism of this type to increase its level ofresistance to tensile loads, since the tensile load acting on therotating mechanism is reduced, the need for increasing the level ofresistance of the rotating mechanism to tensile loads may be small. As aresult, the rotating mechanism may be of a relatively simple structure.

[0023] According to the present invention as described above, anelectric component is preferably mounted on either one of a lower endsurface of said higher upper body and an upper end surface of said lowerupper body, such that said electric component is exposed out when saidrotating mechanism is operated to rotate one of said higher upper bodyand said lower upper body with respect to the other thereof. Theelectric component may comprise an electric component associated withthe electric energy storage device, such as a terminal for charging theelectric energy storage device for operating the robot, or an electriccomponent associated with the electronic circuit unit such as a terminalor a circuit or the like for checking operation of the electroniccircuit unit which controls operation of the robot.

[0024] Since the electric component can be exposed out when one of saidhigher upper body and said lower upper body is rotated with respect tothe other thereof, it is possible to carry out, with ease, maintenanceof the electric component and an operation check on the electriccomponent.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1 is a side elevational view of a bipedal robot, in anupstanding state, according to an embodiment of the present invention;

[0026]FIG. 2 is a simplified front elevational view of an upper body ofthe robot shown in FIG. 1; and

[0027]FIGS. 3 and 4 are views illustrative of the manner in which therobot shown in FIG. 1 operates.

BEST MODE FOR CARRYING OUT THE INVENTION

[0028] An embodiment of the present invention will be described belowwith reference to FIGS. 1 through 4. In FIG. 2, an upper body of a robotis shown, partly omitted from illustration, more simply than in FIG. 1for illustrative purpose.

[0029] As shown in FIG. 1, a bipedal robot according to the presentembodiment is a human-shaped robot having an upper body 1 (torso), legs2, arms 3, and a head 4. Since FIG. 1 is a side elevational view of therobot in an up-standing state, only one leg 2 and only one arm 3 areshown in FIG. 1. However, the robot actually has a pair of left andright legs 2 and a pair of left and right arms 3 like a human being (seeFIG. 2 for the arms 3). The leg 2 and the arm 3 which are illustrated inFIG. 1 are a right leg and a right arm, respectively, as viewed in theforward direction of the robot.

[0030] The upper body 1 of the robot is divided into a higher upper body5 above a hypothetical line X shown in FIG. 1 and a lower upper body 6below the hypothetical line X. The higher upper body 5 comprises ahigher main body 7 to which the arms 3 are coupled and which supportsthe head 4, and a higher auxiliary body 9 for mounting an electricenergy storage device 8 as a power supply for operating the robot. Thelower upper body 6 comprises a lower main body 10 to which the legs 2are coupled, and a lower auxiliary body 12 for mounting a control unit11 (an electric circuit unit having a microcomputer, etc, hereinafterreferred to as ECU 11) for controlling the operation of the robot.

[0031] The higher main body 7 of the higher upper body 5 and the lowermain body 10 of the lower upper body 6 house therein a rotatingmechanism 13, with its axis C of rotation being oriented vertically, forrotating one of the main bodies 7, 10 with respect to the other thereof.The rotating mechanism 13 has an upper end held by a body frame 7 adisposed in and integral with the higher main body 7, and a lower endheld by a body frame 10 a disposed in and integral with the lower mainbody 10.

[0032] Though not shown in detail, the rotating mechanism 13 comprises apair of rotors supported by bearings or the like for rotation relativeto each other about the axis C of rotation as a common axis. One of therotors of the rotating mechanism 13 is fixedly coupled to the body frame7 a of the higher main body 7, and the other rotor is fixedly coupled tothe body frame 10 a of the lower main body 10.

[0033] The higher upper body 5 having the higher main body 7 and thelower upper body 6 having the lower main body 10 is thus operativelycoupled to each other by the rotating mechanism 13 for rotation relativeto each other about the axis C of rotation of the rotating mechanism 13.

[0034] The higher upper body 5 and the lower upper body 6 are rotatedrelatively to each other by an electric motor (not shown) incorporatedin the rotating mechanism 13. In FIG. 1, the upper body 1 is shown asbeing in a basic attitude state in which the higher upper body 5 and thelower upper body 6 have their forward/rearward directions aligned witheach other.

[0035] Shoulders 14 are provided on respective left and right sides ofan upper portion of the higher main body 7 of the higher upper body 5.The arms 3 extend from shoulder joint mechanisms (not shown) placed inthe shoulders 14. Each of the arms 3 has an elbow joint 12 and a wristjoint 17 disposed between a hand 15 and the shoulder 14 and arrangedsuccessively from the shoulder 14. A head 4 which houses an imagingdevice (not shown) for robot vision is fixed to and supported on anupper end of the higher main body 7.

[0036] The higher auxiliary body 9 of the higher upper body 5 is shapedas a casing removably mounted on a rear surface of an upper portion ofthe higher main body 7. The higher auxiliary body 9 has a support member18 disposed therein and fixed to the rear surface of the upper portionof the higher main body 7 for mounting the electric energy storagedevice 8 thereon. The electric energy storage device 8 is removablymounted and supported on the support member 18. The support member 18has a portion 18 a disposed near the higher main body 7 and extendingfrom a position behind the rear surface of the higher main body 7 to aposition behind a rear surface of the head 4. An engaging loop 19(holder) is fixed to the upper end of the portion 18 a and projectsabove the head 4 for engaging a hook (not shown) which is used tosuspend and hold the robot when the robot is inactivated.

[0037] According to the present embodiment, the electric energy storagedevice 8 comprises a rechargeable secondary battery such as a lithiumion battery or the like. However, the electric energy storage device 8may comprise a large-capacity capacitance such as an electricdouble-layer capacitor.

[0038] The lower main body 10 of the lower upper body 6 has a hip 20 atits lower end. The legs 2 extend downwardly from a pair of left andright hip joints 21, respectively, coupled to a parallel link mechanism(not shown) placed in the hip 20. Each of the legs 2 has a knee joint 23and an ankle joint 24 disposed between a foot 22 and the hip joint 21and arranged successively from the hip joint 21.

[0039] The lower auxiliary body 12 of the lower upper body 6 is shapedas a casing disposed immediately below the higher auxiliary body 9 witha slight clearance left between itself and the higher auxiliary body 9,and removably mounted on an upper portion of the lower main body 10. Thelower auxiliary body 12 houses therein a support member 25 fixed to arear surface of the upper portion of the lower main body 10 for placingthe ECU 11 thereon. The ECU 11 is mounted and supported on the supportmember 25.

[0040] A circuit board 26 having an array of terminals for checkingoperation of the ECU 11, for example, is fixedly mounted, as an electriccomponent associated with the ECU 11, on a peripheral edge (corner) ofan upper end surface of the lower auxiliary body 12 near its rearportion. When the robot is in an upstanding state as shown in FIG. 1,the circuit board 26 is concealed by the higher auxiliary body 9directly above the lower auxiliary body 12. When the higher upper body 5is rotated with respect to the lower upper body 6 about the axis ofrotation of the rotating mechanism 13, the circuit board 26 is exposedout.

[0041] Although not shown, the bipedal robot according to the presentembodiment also has, in addition to the above structural details,electric motors for actuating the joints of the legs 2 and the arms 3,sensors for detecting angular displacements of the electric motors(angular displacements of the joints), sensors for detecting loads andmoments acting on the feet 22 of the legs 2 and the hands 15 of the arms3, and sensors for detecting an angle of inclination and an angularvelocity of inclination of the upper body 1.

[0042] The ECU 11 controls the electric motors (including an electricmotor for the rotating mechanism 13) based on information obtained fromthe sensors (including the imaging device in the head 4) and apredetermined program thereby to control operation of the robot (i.e.,to control the walking of the robot through operation of the legs 2, andto control the working of the robot through operation of the arms 3). Inthe present embodiment, the ECU 11 controls operation of the joints ofthe legs 2 based on an inverted pendulum-type dynamic model as disclosedin Japanese laid-open patent publication No. 5-337849 or U.S. Pat. No.5,459,659, for thereby controlling attitude stabilization when the robotwalks and works.

[0043] In the present embodiment, the higher upper body 5 which iscomprised of the higher main body 7 and the higher auxiliary body 9 isof such a size that it has a thickness D in a forward/rearward direction(see FIG. 1, hereinafter referred to as chest thickness D) smaller thana width Wu in a lateral direction at the left and right shoulders 14 ofthe robot (see FIG. 2, hereinafter referred to as shoulder width Wu).The shoulder width Wu is equal to the maximum width in the lateraldirection of the entire upper body 1 (including the shoulders 14) whichis comprised of the higher upper body 5 and the lower upper body 6. Thelower upper body 6 has a width Wd in the lateral direction (which is themaximum width in the lateral direction of the lower upper body 6) alsosmaller than the shoulder width Wu.

[0044] With the bipedal robot of the above structure according to thepresent embodiment, when the rotating mechanism 13 is operated to rotatethe higher upper body 5 with respect to the lower upper body 6 about theaxis of rotation of the rotating mechanism 13 from the basic attitudestate of the upper body 1, one of the left and right shoulders 14 movesforwardly of the lower upper body 6, as shown in FIG. 3. FIG. 3schematically shows the higher upper body 5 and the lower upper body 6as viewed from above. The higher upper body 5 and the shoulders 14 arepositioned as indicated by the solid lines when the upper body 1 is inthe basic attitude state. The higher upper body 5 and the shoulders 14are positioned as indicated by the imaginary lines when the higher upperbody 5 is rotated counterclockwise, for example, about the axis C ofrotation of the rotating mechanism 13. Upon rotation of the higher upperbody 5, the right shoulder 14 is moved forwardly of the lower upper body6 from the basic attitude state.

[0045] As described above, one of the shoulders 14 (the right shoulder14 in FIG. 3) is moved forwardly of the lower upper body 6 when thehigher upper body 5 is rotated with respect to the lower upper body 6about the axis of rotation of the rotating mechanism 13 from the basicattitude state of the upper body 1. Therefore, when the arm 3 extendingfrom the moved shoulder 14 (the right arm 3 in FIG. 3) is extendedforwardly of the lower upper body 6, the hand 15 of the arm 3 can reacha farther position forward of the lower upper body 6 without the needfor moving the robot in its entirety forwardly by operating the legs 2.Thus, the arm 3 can work at the farther position forward of the lowerupper body 6. At this time, since the other shoulder 14 (the leftshoulder 14 in FIG. 3) is moved rearwardly, the rearward arm 3 and theforward arm 3 can easily be balanced in weight even though the forwardarm 3 is extended forwardly of the lower upper body 6, thus easilyachieving the stability of the attitude of the robot.

[0046] The higher upper body 5 can have its forward/rearward directionoriented in various directions by rotating the higher upper body 5 withrespect to the lower upper body 6. Therefore, for gripping an objectpresent laterally of the robot with the arms 3 when the upper body 1 isin the basic attitude state, the legs 2 remain in the same place on thefloor and the higher upper body 5 is rotated with respect to the lowerupper body 6 so as to face the object without the need for moving thelegs 2 to change the orientation of the overall robot. When the higherupper body 5 faces the object, the object can easily be gripped by thearms. Therefore, even if the footing is unstable and any floor areawhere the robot can stand stably is limited to a small area, the legscan remain on such a floor area and the object present laterally of thelower upper body 6 can easily be gripped by the arms 3.

[0047] With the robot according to the present embodiment, as describedabove, the chest thickness D is smaller than the shoulder width Wu, andthe maximum width Wd in the lateral direction of the lower upper body 6is also smaller than the shoulder width Wu. Consequently, when thehigher upper body 5 is rotated with respect to the lower upper body 6,as shown in FIG. 3, the maximum width (Wx in FIG. 3) of the entire upperbody 1 in the lateral direction of the lower upper body 6 in the rotatedstate can be smaller than the shoulder width Wu which is the maximumwidth in the lateral direction when the upper body 1 is in the basicattitude state. As a result, when the robot is to move in a passagenarrower than the shoulder width Wu, the robot can move (walk) byrotating the higher upper body 5 with respect to the lower upper body 6.

[0048] With the robot according to the present embodiment, when thehigher upper body 5 is rotated with respect to the lower upper body 6from the basic attitude state of the upper body 1, as shown in FIG. 4,the circuit board 26 on the peripheral edge of the upper end surface ofthe lower auxiliary body 12 of the lower upper body 6 is exposed out. InFIG. 4, only the higher auxiliary body 9 of the higher upper body 5 andthe lower auxiliary body 12 of the lower upper body 6 are simply shown.

[0049] Therefore, an external device may be connected to the terminalsof the circuit board 26 for checking operation of the ECU 11 with ease.

[0050] With the robot according to the present embodiment, as theelectric energy storage device 8 and the ECU 11 are mounted respectivelyin the higher upper body 5 and the lower upper body 6, the higher upperbody 5 and the lower upper body 6 are balanced in size. Particularly,since the electric energy storage device 8 which is a heavy object ispresent in a high position close to the upper end of the overall robot,the behavioral characteristics of the robot attitude are well inconformity with the behavioral characteristics of an inverted pendulum.As a result, by controlling attitude stabilization of the robot based onan inverted pendulum-type dynamic model, the attitude stabilization ofthe robot can be controlled appropriately for achieving good attitudestability of the robot.

[0051] The ECU 11 which is highly required to avoid overheating ismounted in the lower upper body 6 below the electric energy storagedevice 8. Therefore, heat generated by the electric energy storagedevice 8 during operation of the robot is prevented from being appliedto the ECU 11, which is thus reliably prevented from reachingexcessively high temperatures.

[0052] While the robot according to the present embodiment isinactivated (with its power supply turned off), the robot cannot standon its own. Therefore, the robot is suspended and held by a hook (notshown) engaging the engaging loop 19 (see FIG. 1).

[0053] Since the engaging loop 19 is fixed to the support member 18 ofthe higher upper body 5 which supports the electric energy storagedevice 8 that is a heavy object, the robot can be suspended and heldwhile being kept in an appropriate attitude in which it is unlikely forvarious parts of the robot to be subjected to burdens (excessive loadsor the like) when the robot is suspended. While the robot is beingsuspended, the weight of the lower portion of the robot including thelower upper body 6 acts on the rotating mechanism 13. However, inasmuchas the heavy electric energy storage device 8 is not mounted in thelower portion of the robot, a large load (a tensile load) is preventedfrom being imposed on the rotating mechanism 13. Accordingly, therotating mechanism 13 may have a relatively low level of resistance to atensile load. As a result, the rotating mechanism 13 may be of arelatively simple structure.

[0054] In the embodiment described above, the electric component (thecircuit board 26 in the embodiment) which is exposed out when the higherupper body 5 is rotated with respect to the lower upper body 6 isdisposed on the peripheral edge of the upper end surface of the lowerauxiliary body 12 of the lower upper body 6. However, the electriccomponent may be mounted on a peripheral edge of a lower end surface ofthe higher auxiliary body 9 of the higher upper body 5. The electriccomponent mounted on the peripheral edge of the lower end surface of thehigher auxiliary body 9 may be, for example, a terminal for charging theelectric energy storage device 8 mounted in the higher upper body 5.

[0055] Industrial Applicability:

[0056] The bipedal robot according to the present invention is useful asa robot which moves on two legs and performs various works with twoarms, like a human being.

1. A bipedal robot having two legs extending from a lower end of anupper body and two arms extending from shoulders on opposite sides ofthe upper body, characterized in that said upper body comprises a higherupper body and a lower upper body, said higher upper body and said lowerupper body being coupled to each other by a rotating mechanism having avertical axis of rotation, and being rotatable with respect to eachother about said axis of rotation; and said two arms extend from saidhigher upper body and said two legs extend from said lower upper body.2. A bipedal robot according to claim 1, characterized in that saidhigher upper body has a thickness in a forward/rearward direction whichis smaller than the width in a lateral direction of the robot at saidshoulders, and said lower upper body has a width in the lateraldirection which is smaller than the width in the lateral direction ofthe robot at said shoulders.
 3. A bipedal robot according to claim 1 or2, characterized by comprising an electric energy storage device as apower supply for operating the robot and an electronic circuit unit forcontrolling operation of the robot, and characterized in that saidelectric energy storage device being mounted in said higher upper body,said electronic circuit unit being mounted in said lower upper body. 4.A bipedal robot according to claim 3, characterized in that a holder isfixed to said higher upper body for suspending and holding said robot.5. A bipedal robot according to claim 1, characterized in that anelectric component is mounted on either one of a lower end surface ofsaid higher upper body and an upper end surface of said lower upperbody, such that said electric component is exposed out when saidrotating mechanism is operated to rotate one of said higher upper bodyand said lower upper body with respect to the other thereof.